Thermomechanical Lift-Off and Recontacting of CdTe Solar Cells

Controlled delamination of thin-film photovoltaics (PV) post-growth can reveal interfaces that are critical to device performance yet are poorly understood because of their inaccessibility within the device stack. In this work, we demonstrate a technique to lift off thin-film solar cells from their glass substrates in a clean, reproducible manner by first laminating a polymeric backsheet to the device and then thermally shocking the system at low temperatures ( T ≤ -30 °C). To enable clean delamination of diverse thin-film architectures, a theoretical framework is developed and key process control parameters are identified. Focusing on cadmium telluride (CdTe) devices, we show that the lamination temperature and device architecture control the quality of lift-off, while the rate at which the film stack is removed is controlled by the delamination temperature. Crack-free CdTe devices are removed and successfully recontacted, recovering up to 80% of the original device efficiency. The areal density of these devices is ∼0.4 kg m^-2, a reduction of over an order of magnitude relative to their initial weight on glass. The framework developed here provides a pathway toward both the development of inexpensive, flexible PV with high specific power and the study of previously buried interfaces in thin-film architectures.